Breakage detector for screening apparatus



June 11, 1968 D. L. G. YOUNG BREAKAGE DETECTOR FOR SCREENING APPARATUS 5 Sheets-Sheet 1 Filed July 1.9, 1965 5 Sheets-Sheet 2'5 D. L. G. YOUNG BREAKAGE DETECTOR FOR SCREENING APPARATUS June 11, 1968 Filed July 19, 1965 INVENTOR.

DOUGLAS LG. YOU/V6 BREAKAGE DETECTOR FOR SCREENING APPARATUS Filed July 19, 1965 5 Sheets-Sheet FIG. 6

INVENTOR DOUGLAS L. 6. YOU/V6 United States Patent 0 "ice 3,387,489 BREAKAGE DETECTOR FOR d-CREENING APPARATUS Douglas L. G. Young, Pierrefonds, Quebec, Canada, as-

signor to Canadian Ingersoll-Raud (Jompany Limited,

Montreal, Quebec, Canada, a corporation of (Zanada Filed July 19, 1965, der. No. 473,069 9 Qlainis. (Cl. 73-61) AbSTRACT OF THE DHSCLUSURE Means for detecting a breakage in a screening apparatus, comprising a rotatable shaft carrying a pair of opposing blade members in the discharge of the screening apparatus. One of the blade members is of solid construction; the other is of larger area, but includes a plurality of openings suflicient to cause such one to normally present greater resistance to the discharge. An arm member is connected to the shaft and actuates an electrical switch to set oif an alarm when shive in the discharging blocks the openings in such other blade member.

This invention relates to screening apparatus and has particular reference to the provision of new and improved means for detecting a breakage in a screening apparatus of the type employed to screen a fluid, such as paper pulp fluid, which includes mixtures of fibrous material and liquid.

In the processing of paper pulp lluid, the pulp fluid or stock which is accepted by the pulp screen plate is conventionally discharged thereby to the centrifugal cleaner, dccker, or other apparatus which performs the succeeding step in the paper making process. When a breakage occurs in the pulp screen plate, this discharged stock contains objectional material such as sh-ives and slivers (i.e., unscreened bundles of fibrous material) which pass through the break in the pulp screen plate. This objectional material must be quickly detected; otherwise, the complete contamination of all of the stock in the stock storage system and the production of substandard paper by the paper making machine will result.

An object of the present invention is to provide a new and improved means for detecting a breakage in screening apparatus of the type employed to screen a fluid, such as paper pulp fluid, substantially immediately upon the occurrence of the breakage.

Another object of the invention is to provide a new and improved breakage detection means of the type set forth which signals the operator of the screening apparatus of this breakage immediately upon its detection thereof.

Another object is to provide a new and improved breakage detection means of the type set forth which is highly etlicient and dependable in operation while being relatively simple and economical in construction.

Another object is to provide a new and improved breakage detection means of the type set forth which may be readily and simply cleaned by the pulp fluid screened by the screening apparatus.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings. It will be understood that changes may be made in the details of corn struction and arrangement of parts shown and described as the preferred forms of the invention have been given by way of illustration only. It will, also, be understood that, although the present invention has been herein disclosed with particular reference to a screening apparatus for screening a paper pulp fluid, this embodiment of the invention has been given by way of illustration only. The

3,387,439 Patented June ll, 968

spirit and the scope of the present invention are not limited to screening apparatuses for paper pulp fluid, but rather encompass many other applications of screening apparatuses as will be apparent from the following description.

Referring to the drawings:

FIG. 1 is a partially broken away, perspective view of the screen breakage detection means which is provided by the present invention showing such in a pressurized pipeline mounting in conjunction with a paper pulp screening mechanism;

FIG. 2 is a fragmentary perspective view illustrating the breakage detection means shown in FIG. 1 with the screening apparatus of the paper pulp screening mechanism broken;

FIG. 3 is a fragmentary end view of the breakage detcctz'on means as shown in FIG. 2;

FIG. 4 is a partially broken away, perspective view of a modified form of the breakage detection means shown in FIGS 1 through 3;

PEG. 4A is an enlarged sectional view of that portion of FIG. 4- shown encircled;

FIG. 5 is a perspective view of an alternative embodiment of the present invention in combination with an open channel ilow conduit; and

FIG. 6 is a fragmentary, enlarged perspective view of the embodiment of the invention shown in HG. 5 with the screening apparatus broken.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, FIG. 1 illustrates a paper pulp screening mechanism 1d which receives paper pulp fluid through an inlet 12 and screens it on a screening a paratus or plate 14. The paper pulp fluid or stock accepted by the screening plate 14 passes from the pulp screening mechanism it) by the stock outlet 16 and flows through the accepts fluid pipeline 1% to the centrifugal cleaner, decker, or other apparatus (not shown) which performs the succeeding step in the paper making process. The reject pulp fluid flows from the pulp screening mechanism it) through the reject conduit 20 and is treated in the conventional manner.

The detection means 22 for detecting a breakage in the screening plate 14 is interposed in the fluid pipeline 13 intermediate the pulp screening mechanism 10 and the apparatus (not shown) which performs the succeeding step in the paper making process. As illustrated in FIGS. 1 through 3, the detection means 22 is disposed within a local enlargement 18a of the fluid pipeline 18; it will be understood, however, that the detection means 22 could alternatively be located within one of the regular width portions of the fluid pipeline 18.

More specifically, the illustrated detection means 22 comprises a shaft 24 which is rotatably journalled in the bearings 2e and 28 to bisect the local enlargement 18a and which has an end portion Eda proiecting extenally of the fluid pipeline lb. A first semicircular disc or blade member 3% of solid configuration is fixedly secured to the shaft 24, within the local enlargement 18a of the fluid pipeline in and is adapted for rotation therewith. A second semicircular disc or blade member 32 of slightly larger radius, and hence slightly larger area, than the first blade member 3% is also disposed within the local enlargement 18a and is fixedly secured to the shaft 24 on the side thereof diametrically opposite to that carrying the first blade member 30. Although the first and second blade members 3%) and 32, respectively, are thus both illustrated in H63. 1 through 3 as being of semicircular configuration, it will be understood that they could alternatively be of other suitable construcion providing that sufiicient clearance is left between said blade members and the inside diameter of the fluid pipeline 18 to permit rotation of the blade members with the shaft 24.

The second blade member 32 includes therein a plurality of perforations or openings 34 which are adapted to normally permit the paper pulp fluid or stock in the fluid pipeline is to pass through the second blade member 32. The openings 34 in the second blade member 32 are of such number and dimensions that, although the radius of the second blade member 32 is greater than that of the first blade member 3a, a turning movement is applied to the shaft 24 due to the mean differential pressure or" the stock passing through the fluid pipeline 13 being normally greater on the first blade member 39 than on the second blade member 32.

The end portion 240 of the shaft 25 fixedly carries an extension arm 36 which is limitedly movable within a range determined by the limiting stops 38 and 40 on the support 41. The limiting stop 42 carries an electrical switch 4.2 which is electrically connected by the leads 44 to an alarm apparatus 46 and to a source of electrical power (not shown). The extension arm 36, as will be shown, is adapted to contact the electrical switch 42 to trigger the alarm apparatus 46 upon engagement of the limiting stop 46 by the extension arm 36.

In the operation of the detection means 22 illustrated in FIGS. 1 through 3, with the screening plate 14 unbroken and the openings 34 unblocked, the stock flowing through the fluid pipeline 18 exerts a greater force on the first blade member 30 than on the second blade member 32. Thus, the shaft 24 is rotated until the extension arm 3.6 engages the limiting stop 38 as is shown in FIG. 1.

When the screening plate 14 breaks, however, the stock passing through the fluid pipeline is is contaminated with shives and slivers of fibrous material which pass through the break. These shives and slivers block the openings 34 and, due to the difference in area between the second blade member 32 and the first blade member 30, effect rotation of the shaft 24 until the extension arm 36 engages the limiting stop 46. This engagement of the limiting stop 40 by the extension arm 36 actuates the electrical switch 42 thereon and, as shown in FIG. 2, energizes the alarm apparatus 46 to notify the operator of the pulp screening mechanism 10 of the breakage of the screening plate 14. After the broken screening plate 14 has been replaced, the shives and slivers blocking the openings 34 may be readily and simply removed therefrom by rotating the shaft 24 one-hundred and eighty degrees to permit the stock in the fluid pipeline 18 to wash them from the second blade member 32. After this simple cleaning operation, the detection means 22 is again ready for use.

FIGS. 4 and 4A illustrate a detection means 22a which is a modified form of the detection means 22 shown in FIGS. 1 through 3. As illustrated, in this modification of the invention a lag 48 is fixedly secured to the inside diameter of the fluid pipeline 18 on the screen side of the detection means 22a. A spring or similar resilient member 50 is connected adjacent its opposite ends to the lug 48 and to the second blade member 32 such as to be compressed upon the rotation of the shaft 24 with the screening plate 14 unbroken. The spring is selected such that in its compressed state, with the screening plate 14 unbroken, it will cooperate with the second blade member 34 to return the shaft 2 towards a position wherein the first and second blade members 32 and 34', respectively, are normal to the flow of stock in the fluid pipeline 13.

Thus, in the operation of the detection means 220 the first blade member 32 and the opposing spring 50 and second blade member 34 normally oscillate the shaft 24 when the screening plate 14 is unbroken. Consequently, the extension arm 36 which is carried by the shaft 2d is normally oscillated on the support 41 between its solid 4- and dotted line positions shown in FIG. 4 when the screening plate 14 is unbroken.

The electrical switch 42 for actuating the alarm apparatus 46 to denote a breakage in the screening plate 14 is located in a recess 52 in the support 41. The recess 52 in the support 41 is located therein arcuately outside of the normal angular range of oscillation of the extension arm 36, but within the range of movement of the extension arm 36 when the openings 34 in the second blade member 32 are blocked and the total area thereof assists the spring 51; in rotating the shaft 24.

The extension arm 36, as will be seen from FIG. 4A, carries a locking member 54 which is spring loaded in abutting relation with the support 41 throughout the oscillation of the extension arm 36 by a spring or similar resilient member 56. Upon movement of the extension arm 36 vertically over the recess 52, the spring 56 urges the locking member 54 downwardly into contact with the electrical switch 42 to actuate the alarm apparatus 46. This contact between the locking member 54 and the electrical switch 42 is maintained until the release lever 58 upon the extension arm 36 is manually rotated to cause the locking member 54 to be removed from the recess 52.

Thus, the detection means 22a shown in FIGS. 4 and 4A operates in the following manner. During normal operation of the fluid pulp screening mechanism 10, the second blade member 32 and the spring cooperate to oppose the force of the stock on the first blade member 3a and cause oscillation of the shaft 24. The extension arm 36 which is carried by the shaft 24 is, thereby, oscillated between its solid and dotted positions of FIG. 4. When, however, the screening plate 14 of the pulp screening mechanism 16 breaks, the force of the stock on the second blade member 32 combined with force of the spring 50 effect rotation of the extension arm 36 such that the locking member 54 passes into the recess 52 and energizes the electrical switch 42. Thus, the alarm apparatus 46 is actuated and remains in actuation until the locking member 54 is manually removed from the recess 52.

FIGS. 5 and 6 illustrate an alternative embodiment of a detection means 22b which is particularly adapted for use with a pulp flow in open channels such as is shown in conjunction with a screening mechanism 60 in FIG. 5. As will be seen from FIG. 5, the screening mechanism 60 comprises a cylindrical screening apparatus 62 which receives paper pulp fluid from a fluid inlet (not shown) and discharges accepts paper pulp fluid or stock through a fluid outlet 64- onto an open fluid trough or transporter 66. The open fluid trough 66 transports this stock to the centrifugal cleaner, decker, or other apparatus (not shown) which performs the succeeding step in the paper making process.

The detection means 22b illustrated in FIGS. 5 and 6 com-prises the rectangular first and second blade members 68 and 70, respectively, which are fixedly mounted in diametrically opposing relation upon the shaft 74. The first blade member 68, similarly to the first blade member 30, is of solid configuration. The second blade member 70, similarly to the second blade member 32, is of larger area than the first blade member 68 and includes a plurality of perforations or openings 72 such that the stock in the fluid trough 6t) normally exerts less pressure thereon than on the first blade member 68.

The shaft 74 is journalled for rotation in a bearing 76 which is mounted in a fixed support 78 carried by the fluid trough 66 and fixedly carries an extension arm 80. The extension arm 80 is limitedly movable within the limits dictated by the limiting stops 82 and 84 and, in accordance therewith, limits rotational movement of the shaft 74. The limiting stop 84 carries an electrical switch 86 which is connected to an alarm apparatus 88 and to a source of electrical power (not shown) by the leads Q0. Contact between the extension arm 80 and the electrical switch 86 upon engagement of the limiting stop 84 by the extension arm 80 triggers the alarm apparatus 88 in a manner believed to be apparent from the foregoing description.

The operation and cleaning of this embodiment of the detection means 22b is substantially similar to that of the beforedescri'bed detection means 22 and is believed to be apparent to those skilled in the art from the description of the operation of the detection means 22 taken in view of FIGS. 5 and 6.

In view of the foregoing, it will be seen that I have provided a new and improved breakage detection means for screening apparatus employed to screen a fluid, such as paper pulp fluid, which detection means detects any breakage in the screening apparatus substantially immediately upon its occurrence and then immediately notifies the operator of the apparatus of this breakage. It Will, also be seen that this breakage detection means is highly efficient and dependable in operation yet relatively simple and economical in construction and simple to clean. .7

Fromthe foregoing, it will be seen that I have provided new and improved means for accomplishing all of the objects and advantages of the invention.

Having thus described my invention, I claim.

1. Means for detecting a breakage in screening apparatus ofthe type used to screen a fluid including fibrous material and liquid, comprising:

supporting means;

shaft means carried by said supporting means;

a pair of opposing blade means carried by said shaft means within the discharge of said screening apparatus for rotation by said discharge upon the flow thereof;

one of said pair of blade means presenting greater resistance to the flow of said discharge than the other thereof until breakage of said screening apparatus and shive contaminates said discharge, said other of said pair of blade means presenting greater resistance to the flow of said discharge than said one thereof upon said contamination of said discharge by said shive; and

means responsive to the relative resistance presented by said pair of blade means to the flow of said discharge for denoting when the resistance of said other of said pair of blade means to the flow of said discharge exceeds that of said one thereof.

2. Means for detecting a breakage in screening apparatus of the type used to screen a fluid including fibrous material and liquid, comprising:

a support;

a shaft rotatable on said support;

a first blade member carried by said said shaft within the discharge of said screening apparatus, said first blade member including at least one face of solid construction presenting a resistance to the flow of said discharge;

a second blade member carried by said shaft within the discharge of said screening apparatus, said second blade member including a plurality of openings therethrough; and

means operatively connected to said shaft and responsive to the rotation of said shaft for denoting the breakage of said screening apparatus.

3. Breakage detection means according to claim 2 wherein said second blade member is of larger area than said first blade member, and said plurality of openings in said second blade member are constructed and arranged to reduce the resistance presented by said second blade member to the flow of said discharge below the resistance presented by said solid face of said first blade member to said flow of said discharge when said discharge is uncontaminated by shive.

4. Breakage detection means according to claim 3 wherein said first and second blade members are carried by said shaft upon diametrically opposing sides thereof, and said means for denoting the breakage of said screening apparatus comprises alarm means for signaling the breakage of said screening apparatus.

5. Breakage detection means according to claim 3 wherein a resilient member is operatively connected to said second blade member to permit oscillation of said shaft with said openings in said second blade member unblocked.

6. Breakage detection means according to claim 3 wherein an arm member is fixedly secured to said shaft for rotation therewith, and limiting means cooperate with said arm member to restrict rotation of said shaft.

7. Breakage detection means according to claim 6 wherein said means for denoting the breakage of said screening apparatus is electrically responsive to movement of said arm member to be actuated thereby upon the blocking of said openings in said second blade member.

8. Breakage detection means according to claim 3 wherein an arm member is connected to said shaft for rotation therewith, a resilient member is connected to said second blade member such that when said openings in said second blade member are unblocked said shaft is oscillated to provide oscillation of said arm member through an arcuate path, said denoting means comprises alarm means for signaling the breakage of said screening apparatus, and switch means are connected to said alarm means for operating said alarm means, said switch means being arranged to be actuated by said arm member upon movement of the latter an arcuate distance greater than said arcuate path.

:9. Breakage detection means according to claim 3 wherein an arm member is connected to said shaft for rotation therewith, limiting means cooperate with said arm member for limiting the rotation of said shaft, said denoting means comprises alarm means for signaling the breakage of said screen apparatus, and switch means on said limiting means are connected to said alarm means for operating said alarm means, said switch means being actuatable by said arm member.

References Cited UNITED STATES PATENTS 2,172,399 9/1939 Mueller. 3,276,248 10/1966 Cyr 340239 XR JOHN W. CALDWELL, Primary Examiner. D. M. MYER, Assistaht Examiner. 

